Can I change URL rewrite now without any problem in my PHPLD directory ? OR I need to change any thing else also ?
should be fine. let us hope you are not on godaddy, or 1and1 regardless though, with a few tweaks, you'll be ok.
OK i changed the url rewrite to SEO friendly structure.. I think, my previous deep link building ( /c=101 etc) will be of no use now